Download citation
Download citation
link to html
Low-temperature X-ray diffraction data show that ethyl 2-acetyl-3-oxo-5-phenyl­pent-4-enoate (C15H16O4) exists in the same single enol tautomer in the crystal phase as indicated by spectroscopic data for the compound in solution. The adopted conformation is that with the longest possible conjugation combined with the enol H atom being bonded to the O atom closest to the most electronegative substituent in the planar cinnamoyl acetate unit. Weak hydrogen bonds of the type C—H...O are suggested.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801010583/cv6028sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801010583/cv6028Isup2.hkl
Contains datablock I

CCDC reference: 170884

Key indicators

  • Single-crystal X-ray study
  • T = 123 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.031
  • wR factor = 0.079
  • Data-to-parameter ratio = 11.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry General Notes
REFLT_03 From the CIF: _diffrn_reflns_theta_max 26.38 From the CIF: _reflns_number_total 2813 Count of symmetry unique reflns 1504 Completeness (_total/calc) 187.03% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 1309 Fraction of Friedel pairs measured 0.870 Are heavy atom types Z>Si present no ALERT: MoKa measured Friedel data cannot be used to determine absolute structure in a light-atom study EXCEPT under VERY special conditions. It is preferred that Friedel data is merged in such cases.

Comment top

The reaction of the boron complex of 2-trans-cinnamonyl acetic ethyl ester (CAA) with aromatic or heteroaromatic aldehydes and subsequent acid hydrolysis opened a new procedure for the synthesis of deep coloured β,β'-tricarbonyl compounds (Arrieta, 1993). This was an extension of the Pabon reaction (Pabon, 1964) for β-diketo esters and showed the ability and reactivity of the acetyl group for further condensation reactions. The β,β'-tricarbonyl compounds are interesting molecules also because of the possibility of adopting several different enol tautomer conformations. Thus, the title compound, (4rs), may exist in seven different forms.

Earlier IR spectrographic studies of the title compound (Arrieta et al., 1988) have shown that the carboethoxy group is peripheral and non-coordinating in copper complexes. Moreover, a recent 13C NMR study (Emelina et al., 1999) has indicated that the CAA molecule adopt the (1a) conformation in solution. The postulated chelat bond between the acetyl group and the cinnamonyl group in CAA has been reinvestigated in the solid solution (KBr) and in liquid solution (CHCl3) using IR and NMR spectroscopy. The IR region at 1310 cm-1 in CCl4 was assigned by Forsen (Forsen et al., 1959) to the cinnamonyl group, and probably refers to the group C(O)CHCH. The 13C NMR spectrum in the same solvent confirms, in accord with recent studies (Emelina et al., 1999), the absence of any other tautomers than (1a). The 1H NMR spectrum in CDCl3 shows only one signal for the enol proton (17.60 p.p.m.) in contrast to 2-acetylbenzoylacetates where at least two are found (Sicker et al., 1988). The reason for this seems unclear and NMR studies of such compounds are in progress (Arrieta & Radeglia, 2001). The structural study of 3-benzoyl-6-phenyl-hex-5-ene-2,4-dione (Arrieta et al., 1995), which differ from the title compound only in the exchange of the benzoyl group with a carbethoxy group, showed that the conformation adopted in the crystal phase is that where the longest possible conjugation in the molecule, as well as the positioning of the enol H atom at the oxygen closest to the most electronegative substituent, is simultaneously satisfied. The result of the present investigation shows that the 6-phenylhex-5-ene-2,4-dione parts of the two molecules have virtually identical measures in bond lengths, angles and conformation. This supports the idea that the conjugation and the electronegativities of the enol ring substituents are determining factors for the conformation and the position of the enol H atom. It may be seen from the Scheme, that only conformation (1a) fulfil the two criteria. In the crystal structure of CAA, the molecules related by rotation axes are stacked along the b axis with overlapping enol and carboxylate groups. The distances between the planes through these two groups are 3.423 (2) and 3.391 (2) Å, respectively. The closest contacts between molecules occur through C—H···O interactions. The geometry of these interactions (Table 2) and the fact that such interactions are repeatedly found in the crystal structures of this group of molecules (Mostad, 1994; Arrieta et al., 1995, 2000), indicate that they may be considered as examples of weak hydrogen bonds (Desiraju & Steiner, 1999). A drawing of the molecule with the numbering of the atoms and their vibrational elipsoids is given in Fig. 1. The packing of the molecules is displayed in Fig. 2.

Experimental top

The title compound was synthezized according to a known procedure (Arrieta, 1993). The crystals grown by cooling a saturated warm solution in toluene have a melting point of 318 K. The IR spectra were obtained from a Nicolet 205 F T–IR spectrometer using KBr pellet technique as well as liquid solution (0.4656 M, δ = 2.2 mm) The NMR spectra (1H and 13C) were recorded on Bruker instruments AC 250 and ARX 300. The signals δ = 7.26 p.p.m. 1H and δ = 77.7 p.p.m. 13C for CDCl3 were selected as internal standards. Two characteristic IR absorption bands at 1698 and 1624 cm-1 with about equal intensities (in KBr) were assigned to the non coordinated carbethoxy group and the cinnamonyl group, in coordination with the acyl group, respectively. In chloroform solution (0.47 M), the first band is shifted to 1701 cm-1 (ε = 39 l mol-1 cm-1 and the chelate band to 1630 cm-1 (ε = 44 l mol-1 cm-1. In KBr and CHCl3, a compared profile was found for the bands at 1268 and 1308 cm-1 (KBr) and 1278 and 1308 cm-1 (CHCl3).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. Drawing of the CAA molecule showing the numbering of the atoms and the displacement ellipsoids at a 50% probability level.
[Figure 2] Fig. 2. Stereographic illustration of the molecular packing of CAA molecules in the crystals.
2-acetyl-3-oxo-5-pentyl-pent-4-enoic acid ethyl ester top
Crystal data top
C15H16O4Dx = 1.257 Mg m3
Mr = 260.28Melting point: 45 K
Orthorhombic, Pnn2Mo Kα radiation, λ = 0.71073 Å
a = 21.698 (4) ÅCell parameters from 1024 reflections
b = 7.3390 (15) Åθ = 3.7–26.3°
c = 8.6380 (17) ŵ = 0.09 mm1
V = 1375.5 (5) Å3T = 123 K
Z = 4Needle, yellow
F(000) = 5520.4 × 0.3 × 0.3 mm
Data collection top
Bruker SMART
diffractometer
2813 independent reflections
Radiation source: fine-focus sealed tube2703 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
Detector resolution: 8 pixels mm-1θmax = 26.4°, θmin = 2.5°
ω scansh = 2726
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
k = 99
Tmin = 0.964, Tmax = 0.973l = 1010
13464 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: difference Fourier map
wR(F2) = 0.079All H-atom parameters refined
S = 1.06 w = 1/[σ2(Fo2) + (0.038P)2 + 0.275P]
where P = (Fo2 + 2Fc2)/3
2813 reflections(Δ/σ)max = 0.001
236 parametersΔρmax = 0.13 e Å3
1 restraintΔρmin = 0.16 e Å3
Crystal data top
C15H16O4V = 1375.5 (5) Å3
Mr = 260.28Z = 4
Orthorhombic, Pnn2Mo Kα radiation
a = 21.698 (4) ŵ = 0.09 mm1
b = 7.3390 (15) ÅT = 123 K
c = 8.6380 (17) Å0.4 × 0.3 × 0.3 mm
Data collection top
Bruker SMART
diffractometer
2813 independent reflections
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
2703 reflections with I > 2σ(I)
Tmin = 0.964, Tmax = 0.973Rint = 0.024
13464 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0311 restraint
wR(F2) = 0.079All H-atom parameters refined
S = 1.06Δρmax = 0.13 e Å3
2813 reflectionsΔρmin = 0.16 e Å3
236 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C40.54666 (6)0.30193 (18)0.76650 (17)0.0281 (3)
O10.43932 (5)0.18041 (16)0.90040 (12)0.0424 (3)
O20.54340 (5)0.29967 (15)0.91770 (12)0.0377 (2)
C20.44083 (6)0.18612 (18)0.75416 (17)0.0303 (3)
C30.49602 (6)0.24780 (18)0.67582 (18)0.0267 (3)
C60.65241 (6)0.41141 (19)0.79130 (17)0.0311 (3)
C50.60448 (6)0.36803 (18)0.70073 (16)0.0290 (3)
C70.71294 (7)0.47571 (18)0.73952 (18)0.0319 (3)
C10.38516 (7)0.1190 (2)0.6689 (2)0.0358 (3)
C100.82952 (8)0.6003 (2)0.6492 (3)0.0489 (4)
C80.72895 (8)0.4860 (3)0.5835 (2)0.0445 (4)
C120.75629 (8)0.5312 (2)0.8491 (2)0.0435 (4)
C90.78637 (9)0.5492 (3)0.5391 (3)0.0557 (5)
C110.81407 (8)0.5933 (3)0.8036 (3)0.0508 (5)
O40.44910 (4)0.31302 (13)0.43790 (11)0.0308 (2)
O30.54393 (4)0.19264 (14)0.43011 (12)0.0344 (2)
C140.44371 (7)0.2908 (2)0.27055 (18)0.0345 (3)
C130.50018 (6)0.24626 (17)0.50386 (17)0.0260 (3)
H80.6985 (12)0.452 (3)0.501 (3)0.074 (7)*
H50.6058 (7)0.377 (2)0.5859 (19)0.026 (4)*
H14B0.4419 (8)0.161 (3)0.250 (2)0.035 (4)*
H14A0.4806 (8)0.345 (2)0.223 (2)0.038 (4)*
H1C0.3631 (9)0.221 (3)0.625 (2)0.045 (5)*
H120.7451 (9)0.526 (3)0.951 (3)0.049 (5)*
H1A0.3583 (11)0.053 (3)0.735 (3)0.063 (6)*
H90.7968 (10)0.543 (3)0.419 (3)0.066 (6)*
C150.38452 (9)0.3814 (3)0.2225 (2)0.0466 (4)
H15C0.3873 (10)0.511 (3)0.244 (3)0.062 (6)*
H60.6492 (7)0.4027 (19)0.9022 (19)0.022 (3)*
H15B0.3481 (10)0.326 (3)0.281 (2)0.058 (6)*
H100.8709 (10)0.640 (3)0.617 (2)0.049 (5)*
H110.8433 (10)0.633 (3)0.882 (3)0.060 (6)*
H1B0.3938 (9)0.039 (3)0.582 (2)0.051 (5)*
H15A0.3773 (10)0.370 (3)0.101 (3)0.060 (6)*
H20.4992 (12)0.255 (3)0.938 (3)0.080 (8)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C40.0276 (6)0.0258 (6)0.0309 (6)0.0030 (5)0.0003 (5)0.0003 (5)
O10.0383 (6)0.0518 (7)0.0373 (6)0.0041 (5)0.0098 (5)0.0029 (5)
O20.0348 (5)0.0486 (6)0.0296 (5)0.0033 (5)0.0003 (4)0.0004 (5)
C20.0290 (6)0.0269 (6)0.0350 (7)0.0015 (5)0.0059 (6)0.0006 (5)
C30.0257 (6)0.0225 (6)0.0320 (6)0.0021 (5)0.0022 (5)0.0000 (5)
C60.0303 (7)0.0288 (6)0.0343 (7)0.0022 (5)0.0005 (6)0.0003 (6)
C50.0270 (7)0.0267 (6)0.0333 (7)0.0015 (5)0.0008 (5)0.0009 (5)
C70.0283 (7)0.0271 (7)0.0404 (8)0.0036 (5)0.0031 (6)0.0001 (6)
C10.0278 (7)0.0343 (7)0.0452 (8)0.0037 (6)0.0057 (6)0.0012 (7)
C100.0267 (8)0.0424 (9)0.0777 (12)0.0027 (7)0.0051 (8)0.0064 (8)
C80.0370 (8)0.0527 (9)0.0439 (8)0.0039 (7)0.0028 (7)0.0077 (7)
C120.0374 (8)0.0486 (10)0.0444 (8)0.0040 (7)0.0075 (7)0.0052 (7)
C90.0439 (9)0.0635 (11)0.0596 (11)0.0082 (9)0.0156 (8)0.0057 (9)
C110.0332 (8)0.0457 (9)0.0734 (13)0.0051 (7)0.0155 (8)0.0077 (8)
O40.0288 (5)0.0349 (5)0.0288 (5)0.0034 (4)0.0003 (4)0.0018 (4)
O30.0269 (5)0.0436 (6)0.0326 (5)0.0027 (4)0.0031 (4)0.0041 (4)
C140.0350 (7)0.0399 (8)0.0286 (7)0.0012 (6)0.0001 (6)0.0022 (6)
C130.0233 (6)0.0235 (6)0.0312 (6)0.0016 (5)0.0009 (5)0.0009 (5)
C150.0508 (10)0.0535 (10)0.0355 (8)0.0143 (8)0.0076 (7)0.0009 (8)
Geometric parameters (Å, º) top
C4—O21.3081 (18)C10—C111.376 (3)
C4—C31.4066 (19)C10—C91.386 (3)
C4—C51.4601 (18)C10—H100.98 (2)
O1—C21.2643 (18)C8—C91.384 (2)
O1—H21.45 (3)C8—H81.00 (3)
O2—H21.03 (3)C12—C111.391 (2)
C2—C31.4481 (19)C12—H120.92 (2)
C2—C11.498 (2)C9—H91.06 (2)
C3—C131.4882 (18)C11—H110.97 (2)
C6—C51.3398 (19)O4—C131.3390 (16)
C6—C71.466 (2)O4—C141.4594 (18)
C6—H60.963 (16)O3—C131.2091 (17)
C5—H50.994 (16)C14—C151.505 (2)
C7—C81.394 (2)C14—H14B0.972 (18)
C7—C121.395 (2)C14—H14A0.986 (18)
C1—H1C0.96 (2)C15—H15C0.97 (2)
C1—H1A0.95 (2)C15—H15B1.02 (2)
C1—H1B0.97 (2)C15—H15A1.07 (2)
O2—C4—C3120.67 (13)C9—C8—C7120.73 (17)
O2—C4—C5116.06 (12)C9—C8—H8118.6 (15)
C3—C4—C5123.25 (14)C7—C8—H8120.6 (15)
C2—O1—H2101.0 (11)C11—C12—C7120.78 (18)
C4—O2—H2103.2 (15)C11—C12—H12121.8 (12)
O1—C2—C3119.92 (14)C7—C12—H12117.4 (12)
O1—C2—C1117.34 (13)C8—C9—C10120.54 (19)
C3—C2—C1122.68 (14)C8—C9—H9116.7 (12)
C4—C3—C2118.30 (14)C10—C9—H9122.4 (12)
C4—C3—C13120.71 (12)C10—C11—C12120.39 (17)
C2—C3—C13120.94 (12)C10—C11—H11120.5 (13)
C5—C6—C7126.44 (14)C12—C11—H11119.1 (13)
C5—C6—H6120.6 (9)C13—O4—C14116.54 (11)
C7—C6—H6113.0 (9)O4—C14—C15106.98 (13)
C6—C5—C4121.24 (13)O4—C14—H14B107.3 (11)
C6—C5—H5122.9 (9)C15—C14—H14B110.3 (10)
C4—C5—H5115.8 (9)O4—C14—H14A107.7 (10)
C8—C7—C12118.16 (15)C15—C14—H14A113.4 (10)
C8—C7—C6122.41 (14)H14B—C14—H14A110.8 (15)
C12—C7—C6119.42 (14)O3—C13—O4123.01 (13)
C2—C1—H1C109.7 (11)O3—C13—C3125.16 (13)
C2—C1—H1A111.5 (14)O4—C13—C3111.83 (11)
H1C—C1—H1A109.1 (17)C14—C15—H15C109.0 (13)
C2—C1—H1B115.0 (12)C14—C15—H15B110.3 (12)
H1C—C1—H1B105.4 (16)H15C—C15—H15B110.1 (18)
H1A—C1—H1B105.9 (17)C14—C15—H15A111.3 (12)
C11—C10—C9119.37 (16)H15C—C15—H15A106.1 (17)
C11—C10—H10120.5 (11)H15B—C15—H15A109.9 (16)
C9—C10—H10120.2 (11)
O2—C4—C3—C21.27 (19)C6—C7—C8—C9179.36 (16)
C5—C4—C3—C2179.44 (12)C8—C7—C12—C110.6 (2)
O2—C4—C3—C13178.58 (12)C6—C7—C12—C11179.83 (16)
C5—C4—C3—C133.2 (2)C7—C8—C9—C101.2 (3)
O1—C2—C3—C40.7 (2)C11—C10—C9—C82.1 (3)
C1—C2—C3—C4177.69 (13)C9—C10—C11—C121.6 (3)
O1—C2—C3—C13176.65 (12)C7—C12—C11—C100.3 (3)
C1—C2—C3—C130.4 (2)C13—O4—C14—C15177.93 (12)
C7—C6—C5—C4178.81 (12)C14—O4—C13—O310.01 (19)
O2—C4—C5—C64.40 (19)C14—O4—C13—C3170.26 (11)
C3—C4—C5—C6177.34 (13)C4—C3—C13—O342.0 (2)
C5—C6—C7—C85.0 (2)C2—C3—C13—O3135.22 (14)
C5—C6—C7—C12174.17 (15)C4—C3—C13—O4137.70 (12)
C12—C7—C8—C90.2 (3)C2—C3—C13—O445.06 (17)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O11.03 (3)1.45 (3)2.427 (2)157 (2)
C10—H10···O2i0.98 (2)2.79 (2)3.707 (2)155 (2)
C11—H11···O3ii0.97 (2)2.52 (2)3.349 (2)143 (2)
Symmetry codes: (i) x+3/2, y+1/2, z1/2; (ii) x+3/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC15H16O4
Mr260.28
Crystal system, space groupOrthorhombic, Pnn2
Temperature (K)123
a, b, c (Å)21.698 (4), 7.3390 (15), 8.6380 (17)
V3)1375.5 (5)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.4 × 0.3 × 0.3
Data collection
DiffractometerBruker SMART
diffractometer
Absorption correctionEmpirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.964, 0.973
No. of measured, independent and
observed [I > 2σ(I)] reflections
13464, 2813, 2703
Rint0.024
(sin θ/λ)max1)0.625
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.079, 1.06
No. of reflections2813
No. of parameters236
No. of restraints1
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.13, 0.16

Computer programs: SMART (Bruker, 1998), SMART, SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
C4—O21.3081 (18)C3—C131.4882 (18)
C4—C31.4066 (19)C6—C51.3398 (19)
C4—C51.4601 (18)C6—C71.466 (2)
O1—C21.2643 (18)O4—C131.3390 (16)
O1—H21.45 (3)O4—C141.4594 (18)
O2—H21.03 (3)O3—C131.2091 (17)
C2—C31.4481 (19)C14—C151.505 (2)
C2—C11.498 (2)
O2—C4—C3120.67 (13)C2—C3—C13120.94 (12)
O2—C4—C5116.06 (12)C5—C6—C7126.44 (14)
C3—C4—C5123.25 (14)C6—C5—C4121.24 (13)
C2—O1—H2101.0 (11)C8—C7—C6122.41 (14)
C4—O2—H2103.2 (15)C12—C7—C6119.42 (14)
O1—C2—C3119.92 (14)C13—O4—C14116.54 (11)
O1—C2—C1117.34 (13)O4—C14—C15106.98 (13)
C3—C2—C1122.68 (14)O3—C13—O4123.01 (13)
C4—C3—C2118.30 (14)O3—C13—C3125.16 (13)
C4—C3—C13120.71 (12)O4—C13—C3111.83 (11)
C4—C3—C13—O342.0 (2)C4—C3—C13—O4137.70 (12)
C2—C3—C13—O3135.22 (14)C2—C3—C13—O445.06 (17)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O11.03 (3)1.45 (3)2.427 (2)157 (2)
C10—H10···O2i0.98 (2)2.79 (2)3.707 (2)155 (2)
C11—H11···O3ii0.97 (2)2.52 (2)3.349 (2)143 (2)
Symmetry codes: (i) x+3/2, y+1/2, z1/2; (ii) x+3/2, y+1/2, z+1/2.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds